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Discussion Starter · #1 ·
When I bought my 04 race bike, it had stock headers with the left side outlet welded shut, a small diameter mid pipe next to the swing arm, and then going to a single 2.25” under tail and muffler. The weld job really constricted they mid pipe just after the front and rear pipe comes together. I suspect that it is less than ideal. I do like the idea of an undertail muffler for crashing purposes.
I bought a TIG welder this past winter. I started this project to learn how to weld stainless steel. I bought a Jardine 2-1 header with no muffler from a member here. The pipe was header wrapped and it really weakened the metal. The 2-1 collector was too thin and brittle to weld to. So I ended up making my own based on similar dimensions of the Jardine piece. I then used 304 SS 2.25” pipe and welded it to the collector and ran it behind the foot rest in the swing arm recess up to the existing under tail muffler. My welds are not great, but I think they will work. I blew a few holes before I realized that I needed to turn the power way down The pipe is very solid mounted. I dont expect anyone to think it is from the aftermarket, and it doesn’t look pretty, but if it works and I gain a little power, then good enough for a race bike.
 

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Discussion Starter · #3 ·
I got my bike out of the shop today with this dyno print out. The previously cobbled together crap pipe was killing the midrange. My newly fabricated mid pipe increased midrange power by 10hp between 5800rpm and 7400 rpm. I should get better drives out of the corners now. I try to keep it between 7k rpm and 9500k rmp during races.
No change in the top end. I suspect that is the single muffler to blame for that one. But good enough for me. Good enough for my old race bike. Gained 10hp by spending $100 on the mid pipe. Still cost me more money with the tune, but it was still cheaper than a new system, My single under-tail muffler is more crash proof and lighter than the dual system. And I got to learn how to TIG weld stainless so I can do it again if I need to.

Blue line is custom cobbled crap stock header, strangled off mid pipe, and single under-tail muffler
Red line is Jardine header, custom 2.25” mid-pipe to single under-tail muffler
Tuned with a PowerCommander V
 

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